SCIENCE 
——<— | 
Fripay, June 14, 1912 
CONTENTS 
The American Association for the Advance- 
ment of Science :— 
Some Current Conceptions of the Germ 
Plasm: PRoFessor R. A. HARPER ........ 909 
Scientific Notes and News ........+.0..0005 923 
University and Educational News .......... 925 
Discussion and Correspondence :— 
The Nature of the Inheritance of Horns in 
Sheep: Proressor T. R. ARKELL, PRo- 
FEssor C. B. DAVENPORT. 
Schools: L. S. HAWKINS 
Agriculture in 
927 
Scientific Books :— 
Jones and Strong’s The Absorption Spec- 
tra of Solutions of Comparatwely Rare 
Salts: Dr. FREDERICK H. GETMAN. Mac- 
Donald’s Historical Papers on Modern Ex- 
plosives: PROFESSOR CHARLES E. MUNROE. 
Sanderson on Insect Pests: PROFESSOR W. 
E. Brrrron 928 
Terms Used to Denote the Abundance or 
Rarity of Birds: JOHN DRYDEN KUSER .. 930 
Trivalent Platinum: J. L, H. ............. 931 
Special Articles :— 
Simple Demonstration Apparatus for the 
Infra-red Spectrum: PROFESSOR AUGUSTUS 
TROWBRIDGE 931 
The American Society of Zoologists:— 
Proceedings of the Central Branch: Pro- 
MESSORMWe CA CURTIS Me rriisleielssriseteieielere 
MSS. intended for publication and books, etc., intended for 
review should be sent to the Editor of SctENCE, Garrison-on- 
Hudson, N. Y. 
SOME CURRENT CONCEPTIONS OF THE 
GERM PLASM 
Ir is a commonplace of observation that 
the first decade of the present century has 
been, so far as the study of heredity and 
the germ plasm is concerned, a period of 
observation and experimentation, rather 
than of theorizing. The speculations as to 
a physical basis of heredity and its ultimate 
structure, which began with Naegeli’s con- 
ception of the idioplasm and micelle and 
culminated in Weismann’s elaborate system 
of ultra-microscopic bearers and deter- 
miners of heredity and development, have 
given place to a renewed activity of obser- 
vation on the structure and functions of 
the cell in reproduction and especially to 
experimentation in hybridizing and all 
forms of plant and animal breeding. We 
need not go so far as to say that evolution 
was on its death bed before the Mendelian 
revival. The study of the ultimate struc- 
ture and processes of the plant cell has gone 
on from Von Mohl’s time at least without 
much regard to such highly speculative 
disciplines as natural selection, Neo-La- 
marckianism, neo-vitalism, ete.; still there 
can be no question that with the rediscov- 
ery of Mendelism and the possibility of 
bringing a great mass of both breeding and 
cytological data, as to unit characters, 
gametic purity, segregation and germinal 
variation and the behavior of the chro- 
mosomes in nuclear division and fusion, 
synapsis and reduction, into one harmoni- 
ous theory of development, a great impetus 
has been given to the study of the funda- 
+ Address of the vice-president and chairman of 
Section G, Botany, American Association for the 
Advancement of Science, December, 1911. 
